The young couple who are my neighbours have now acquired two puppies and two cats. They all seem delightful. Well, as delightful as cats can be when they are interested in one's goldfish.
The solution that I had found to keep the seagulls off seemed unlikely to deter this curious chap.
So another deterrent had to be found
and this is it: floating plastic interconnecting grids which prevent the cat from getting into the pond or scooping the fish out and at the same time preventing the gulls swooping down. What's more for most of the time they can hardly be seen